1. Technical Field
The embodiments of the present invention relates to the field of display, and particularly to an array substrate and a manufacturing method thereof, and a display apparatus.
2. Description of the Related Art
Active Matrix Organic Light Emitting Diode (AMOLED) display apparatus is an important structural form of an OLED display apparatus, and comprises an array substrate and a package substrate. A plurality of display units are formed on the array substrate. As shown in FIG. 1, the display unit comprises a switching thin film transistor 3, a driving thin film transistor 4, and an OLED. The switching thin film transistor 3 has a gate G electrically connected with a gate line 1, a drain D electrically connected with a data line 2, and a source S electrically connected with a gate G of the driving thin film transistor 4. The driving thin film transistor 4 further has a drain D electrically connected with a Vdd line (power supply and signal line), and a source S electrically connected with an anode or cathode of the OLED. When electrical signals are loaded on the gate line 1, the data line 2, and the Vdd line simultaneously, the OLED is driven, by the source S of the driving thin film transistor 4, to emit light.
In the above mentioned AMOLED display apparatus, as shown in FIG. 2, an active layer 13 is generally formed of Indium Gallium Zinc Oxide (IGZO) having greater electron mobility, while an etch stop layer 14 is generally further formed on the active layer 13 to prevent the active layer 13 from being eroded when a drain 17 and a source 18 are wet-etched by acid solution.
Specifically, as shown in FIG. 2, the drain 17 and the source 18 of the switching thin film transistor 3 are electrically connected to the active layer 13 through first via holes 15, the source 18 of the switching thin film transistor 3 is electrically connected to a first electrode 20 through a second via hole 16, and the first electrode 20 is electrically connected to a gate 11 of the driving thin film transistor 4. During manufacturing, the first via holes 15 and the second via hole 16 are formed by simultaneously etching by means of a single mask. It is only necessary to etch a single layer, i.e., the etch stop layer 14, so as to form the first via holes 15, thereby achieving electric connection between the source and the drain and the active layer, and it is necessary to etch two layers, i.e., the etch stop layer 14 and a gate insulating layer 12, so as to form the second via hole 16. Therefore, when the second via hole 16 is formed by etching, the first via holes 15 will be over-etched. In other words, the first via holes 15 will pass through the etch stop layer 14 and the gate insulating layer 12 so that the source 18 and the drain 17 are both electrically connected to the gate 11, thereby resulting in failure of the switching thin film transistor.
In order to avoid the abovementioned problem, in a conventional manufacturing technology, the first via holes and the second via hole are formed by means of use of two mask processes or use of a half-tone mask and a gray-tone mask. However, the use of the two mask processes increases complexity of technology and production cost, while the use of the half-tone mask and the gray-tone mask also increases production cost since the half-tone mask and the gray-tone mask are expensive although only one mask process is used.